The lights are important because not only do they help your visibility, but it can also help others to see where you at or which direction you are turning. Also make sure the light is still operating. It is easier than you might think to smash a headlight or taillight on your vehicle. You might reverse into a parking space in the dark and not see a pillar or rail sticking out ready to crunch into your taillight.
If the headlight or taillight is not operating correctly, knowing if it should be replaced completely can be determined on the condition. It will depend how badly the light has been smashed or damaged. If half of it is missing and the other half is in tiny shards, you are not going to be able to do a proper repair job. Any damage that you notice should be repaired as soon as possible. You can bring the vehicle in and we can inspect the lights for you.
The headlights allow you to see, as well as oncoming traffic and people to see you. The taillights are also important because drivers that are approaching you will be able to see where you are. This will increase the overall safety of your vehicle. The turn signals are also important because those around you will know what direction you will be turning. This can help prevent an accident if someone tries to pass you on the side or in front of you while you are turning.